Controller for electric motors.



J. DLSMON'D. CONTROLLER FOL ELECTRIC MOTORS.

APPLICATION FILED DC. 13, 1909.

Patented 5311.7

JOHN DESMOND, OF CHICAGO, ILLINOIS, ASSIGNOR T0 ARTIZAN BRASS COMPANY,OF

CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

CONI.I|R.OII' LERv FOR ELECTRIC MOTORS.

' Specication of Letters Patent.

Patented J al1. 7, 1913.

Application filed December 13, 1909. Serial No. 532,857.

To all 'whom t may concern:

Be it known I, JOHN DEsMoND, a citizen of the United States, residing atChicago, in the county of Cook and State of Illinois, have inventedcertain new and useful Improvements in Controllers for Electric Motors,of which the following is a specification.

My invention relates to controllers for electric motors and has especialreference to automatic controllers for starting and stopping an electricmotor, upon the occurrence of a variation from a predetermined conditionto be established and maintained in the device with which said motor isassociated.

One of the objects of my invention is to provide a new and improveddevice of the character described.

In the drawings, Figure 1 is an elevation of the device shown associatedwith an electric motor `used to compress air within a tank; Fig. 2 is anenlarged elevation of a portion of 'the controller taken at right anglesfrom that shown in Fig. 1; Fig. 3 is a broken-away enlarged lowerportion of the device in section as illustrated in Fig. 1; and Fig. 4 isa similar view of the upper portion of the device.

In all of the views the same reference characters indicate similarparts.

10 indicates, generally, an air tank within which air under compressionis to be stored and normally maintained at a selected predeterminedpressure.- An. air fcompressor, 12, is, for convenience, mounted.: onthe tank and connected thereto by means of pipe 11. An electric motor,14, is connected to the compressor by means of any suitable gearing, inthe single embodiment illust-rated being directly connected thereto.

The controller, 15, is connected to the tank 10 and supported thereon bypipe, 16. A diaphragm casing, 17, is composed of two parts, 17a and 17",the latter lhaving screwthreaded connection with the pipe 16, asclearlyshown at 18. A `diaphragm is firmly held between the two parts of thecasing 17 by bolts, 20. The part '17a has a central, cylindrical,screw-threaded projection, 17 c, upon which are mounted a stationaryarm, 21, and a relatively movable arm,

. 22. The latter is pivoted, as at 23 to a screw-threaded support, 211.A check nut,

25, holds the support 24 in adjusted position in the projection 17C fora purpose to be hereinafter described.

The upper portions of the arms, 21 and 22, are composed of insulatingmaterial, 21 and 22', respectively. The arm 22 is provided with aninwardly-projected heel, 26. A stem, 27, is pointed at its smaller end,as at 28, for engagement in a depression of the heel 26. The stem 27 isprovided with an enlarged head, 29, forvvertically guiding the stemwithin the cylindrical projection 17. The lower end of the pin 27 restsupon the top of the diaphragm.

Upon the upper insulating ends of the arms, 21 and 22, is carried anelectric switching device for opening and closing an electric circuitfor controlling an electric motor. The switch consists of the metallicstrip, 30, bent over the end of the insulating extension, 21', of thearm 21 and held in place by the terminal binding screw, 31, the

contact of the strip being beveled, as at 32.l

A coperating terminal, 33, is secured in a similar manner to the part 22by a terminal screw, 34. The strip 33 is made longer than actuallynecessary to bridge the ends of the arms 21 and 22 and is bent back uponitself, as at 35, to render it more elastic, that it may make frictionalcontact with its cooperating terminal without undue friction between theparts.

An adjusting spring, V36, serves to hold the arms, 21 and 22, insubstantially parallel relation and the switch .,closed. Circuit wires,37, 38, and 39, are portions of a circuit for including the controllingdevice and motor in circuit withr` any suitable source of electriccurrent,

The operation of the device is as follows: The motor, 14, is started inthe usual manner. which pumps air into the tank 10, through -the pipe11. When the air Within the tank has reached a predetermined pressure,the center of the diaphragm 19 is thereby raised, the stein 27 iscorrespondingly lifted and operating under the heel 26 it moves thelever 22 against spring 36 to break contact between the switch terminals30-33. It is very desirable to make a quick break between the switchterminals and it is also advantageous to have the motor run foraconsiderable period of time and to correspondingly prolong the intervalsminals,

` passed, the

workingperiods of the motor. To this end, I provide a variable,switch-moving device, comprising a latch lever, 40, pivoted to one ofthe arms, as at 41, and projecting beyond the companion arm, as at 42. Awearing plate, 43, preferably of hardened steel, is held rigidly by ascrew, 44, on the arm 22.- The latch lever 40 is held in yieldingcontact with the plate 43 by the spring 45. On the under surface of thelatch 40 is provided an inclined shoulder, 46. When pressure is appliedupon the diaphragm to separate the vertical arms to open the switch, theplate 43 is brought into contact with the inclined shoulder, 46, beforeconnection is 'broken between the switch ter- 30-33. When pressurewithin the tank is further augmented the plate 43 lifts the latch 40against. the effect of the spring, 45, by the instrumentality of thetapered shoulder 46. After the shoulder has been movement of t-he arm 22is very rapid, being relieved of the resistance of the latch device 40,the switch terminals being quickly separated, and the motor stops. Whenthe air pressure within the tank is decreased sniiciently, the spring 36draws the arm 22 toward the arm 21 and thereby the switch isautomatically closed and the motor again started. Considerable variationin the pressure to be normally maintained within the tank may be made byadjustment of the tension of thel spring, 36, by means of thescrew-threaded nut 36. Further variation in maintained pressure may bemade by adjusting the support 24 on the projection 17' and securing itin adjusted position by the check nut 25.

While I have thus described in some detail a single embodiment of myinvention, it will be understood by those skilled in the art that theparticular construction and arrangement might be considerably variedwithout departure from the spirit of the invention, and I do not desireto be understood as limiting the invention to such particularembodibetween .the

ment further than is specified in the follow--v ing claims.

What I claim is:

1. In a switch mechanism, the combination of a diaphragm, a casingsupporting said diaphragm, a frame adjustable toward and from saiddiaphragm, vertically disposed parallel arms, one fixed and one pivotedat its lower end to said adjustable frame, switch terminals carried bythe upper ends of said arms, and a member movable lby saidv diaphragm toabut against the end of said pivoted arm, whereby adjustment of saidframe may vary the position of abutment between said member and thepivoted arm.

2. In a motor controller, a pressure-responsive device, a casingtherefor, a stem movable by said pressure-responsive device, a switcharm providing an abutment for coaction with said stein, and ascrewthreaded support for `said arm, said casing providing ascrew-threaded projection for reception'thereof, and said stem andabutment lying in the axial center of said support and projection,whereby turning of said support upon said projection varies the eectivedistance between said abutment and' stem.

3. .The combination of two vertical arms, one whereof is pivotallymounted, contacts separable upon pivotal movement -of said arm, a springnormally holding the arms together, one arm having a slot therein,presenting a latch-engaging edge across said slot, a latch pivoted tothe other arm, eX- tending through the slot, and having a taperedshoulder for engagement of said plate, and a spring tending to hold saidlatch against the plate.

In testimony whereof I hereunto set my hand in the presence of twowitnesses.

JOHN DESMOND.

In the presence of W. LrNN ALLEN, MARY I". ALLEN.

a plate

